Log debarkers



March 27, 1962 E. o. LUNN 3,026,

LOG DEBARKERS Filed April 27, 1960 E 2 Sheets-Sheet 1 IN VENTOR EDWARD O LUNN March 27, 1962 E. o. LUNN 3,026,919

LOG DEBARKERS Filed April 27, 1960 2 Sheets-Sheet 2 v HELICAL PATH OF TOOL ON LOG SURFACE INVENTOR EDWARD O. LUNN y wig/$6 47,

limited States Patent 3,026,919 LOG DEBARKERS Edward 0. Lunn, Vancouver, British Columbia, Canada, assignor to Sydney Hansel, Edmonds, Wash. Filed Apr. 27, 1960, Ser. No. 24,989 1 Claim. (Cl. 144--208) My invention relates to improvements in log debarkers.

This invention pertains to a bark-removing machine of the type having an annular rotor with tools carried by the rotor and adapted to strip bark from a log being fed axially through said rotor.

The objects of the invention are to provide resilient means for moving the tools into engagement with the log and to provide mechanical means controlled by the debarker .operator for swinging the tools toward the periphery of the rotor.

A further object is to provide for such a debarker a tool which will remove bark from the log by a chisellike cleaving action rather than by the crushing or shearing action of the conventional bark-removing machines.

A still further object is to provide a tool having a raker element which tends to hold the tool in engagement with the log surface so as cleanly to remove the bark from a log of irregular section.

These and other objects will appear in the following specification and be shown in the accompanying drawing in which:

FIGURE 1 is an elevation of the back or outfeed side of the debarker.

FIGURE 2 is a section taken on line 2-2 of FIGURE 1.

FIGURE 3 is a diagrammatic side elevational view showing the position of the debarker with respect to the log conveyor.

FIGURE 4 is a fragmentary view, part in section, of a modified form of the tool supporting arms.

FIGURE 5 is an enlarged section of the bark-removing tool taken on the line 5-5 of FIGURE 2.

FIGURE 6 is a section taken on line 6-6 of FIGURE 5.

FIGURE 7 is a plan of the tool acting upon a log surface.

In the drawings like characters of reference indicate corresponding parts in each figure.

The present debarking machine consists of a frame 10 which supports a rectangular stator 11. An annular rotor 14 is journalled in the stator and is adapted to be driven in the direction of the arrow 15 of FIGURE 1 by suitable means, not shown. A log conveyor 16, see FIGURE 3 only, is adapted to feed logs 17 through the centre of the rotor 14 and hold-down rolls '18 are provided to support the logs against rotation as they are fed axially through said rotor in the direction of the arrow 19. A similar log debarker and feed mechanism therefor has been fully described in my United State Patent 2,843 ,168 and no further detailed description of this portion of the structure is deemed to be necessary.

The annular rotor 14 may be formed of channel section to provide an outfeed flange 21, an infeed flange 22 and a connecting web 23. Equidistantly spaced around the rotor are a suitable number of horizontal pivot pins 25 which extend between the flanges 21 and 22 and are journalled in bearings 26. Secured to each pin 25 is an arcuate arm 28 having side edges 29 and 30. The edge 30 is the first part of the arm contacted by the leading end of a log being fed through the rotor and for this reason said arm is curved as shown in FIGURE 2, so that said arm will ride smoothly up on the periphery of the advancing log. The edge 29 of the arm is also curved to enable the arm to close or drop oi? the trailing end of the log as it leaves the debarker.

The pins project beyond the outfeed flange 21 of the rotor and secured to the projecting end of each pin is a lever 3-4. The inner end of the levers 34 are fitted with rotatably mounted pulleys 35 and trained over the pulleys is an endless resilient band 36. As shown best in FIGURE 1 the band 36 tends to swing the levers 34 in a counter clockwise direct-ion and since the arms 28 are also secured to the pins 25 said arms are urged toward the centre of the rotor by the action of the resilient band. A sheave 38 is mounted on the outer end of each lever 34 which sheave has a cable rim of sufiicient width to accommodate two lays of cable or the like.

Above the rotor 14 a centrally disposed horizontal cylinder 40 is mounted upon the stator 11 which cylinder may be of the hydraulic or pneumatic type. Opposing pistons 41 are fitted to the cylinder 40 and mounted on the outer end of each piston is a vertically disposed sheave 42. An endless flexible member 43 is passed over the sheaves 42 and is crossed beneath the cylinder 40 to form a bight 44. The sheaves 38 carried v by the levers 34 engage the bight 44 and are adapted to travel there around as the rotor revolves within the stator. It will be noted that the member 43 is of spring steel rod so that the bight 44 will assume a hoop-like form as shown in FIGURE 1. Alternatively a length of cable may be used to form the member 43.

In the modification shown in FIGURE 4 each pivot pin 25 is fitted with a lever 47 and integrally formed on the outer end of said lever is a grooved shoe 48. The bight 44 in the flexible member 43 is slidably engaged by the grooved shoes 48. A spring 50 is secured to each arm 28 and is anchored to the rotor 14 to swing said arms and the levers 47 in a counter-clockwise direction.

Secured to the inner end of each arm 28, by bolts 53, is a bark-removing tool 54, see particularly FIGURES 5, 6, and 7. The tool 54 has an outer wall 56 and a rounded end wall 57. On the end wall 57 a raker 58 having a plane face 59 is formed, the face being disposed in parallel relation to the axis of the rotor 14. The walls 56 and 57, on the infeed side of the rotor, are connected by a web 60 and the inner edge of said Web is sharpened to provide a side cutter 61.

In operation a log 17 is fed by the conveyor 16 toward the debarker and the rotor 14 is driven at a suitable operating speed. The debarker operator estimates the diameter of the advancing log and pressurizes the cylinder 40 to position the tools 54 at a spacing slightly less than the log diameter. Movement of the pistons 41 away from the centre of the debarker will obviously contract the bight 44 and swing the arms 28 away from the rotor axis against the tension of the resilient band 36. As the arms 28 are contacted by the leading end of the log they will be moved outwardly a further short distance by virtue of their curved edges 30 and the tools 54 will be held in contact with periphery of the log by the resilient pressure of the band.

The tools being rotated about an axially moving log describe a helical path thereon and the side cutter 61 slices through the bark down to the cambium layer of the wood and severs from the bark a narrow band substantially the width of the raker 58. This band of bark is scraped from the log by the raker 58 and very little effort is required to break the adhesion of the bark to the log surface.

It will be noticed in FIGURE 5 that the face 59 of the raker 58 is disposed at an acute angle 64 to a radial line extending from the center of the log. The relatively moving band of bark engages the inclined raker face and exerts a force thereon which tends to hold the tool in contact with the log surface. This holding force augments the resilient force applied by the band 36, so that the tool is held firmly in contact with the log at all 3 times. Thus a log having an irregular surface is cleanly stripped of its bark without the tendency of the tools to jump over obstructions and leave patches of bark adjacent to said obstruction.

The rounded end walls 57 of the tools slide easily over the peeled surface of the log without gouging or otherwise damaging the wood.

The operation of the modified form of the debarker is as above described with the resilient force urging the arms 28 towards the center of the rotor being applied by the springs 50.

What I claim as my invention is:

In a log debarker having a stator, an annular rotor mounted in the stator and means for feeding logs axially through the rotating annular rotor, a plurality of arms carried by the rotor, each of said arms being mounted for swinging movement in a plane disposed at right angles to the axis of the rotor, a bark-removing tool carried at the inner end of each arm, said tool having a side cutter adapted to sever from a log a helical band of bark and a raker adapted to remove the helical band of bark from the log surface, said raker having a face disposed in parallel relation to the axis of the log and at an acute angle to a radial line extending from the center of the log and through the raker, means for holding the tool up to its work and means for swinging the tool towards the periphery of the debarker.

References Cited in the file of this patent UNITED STATES PATENTS 1,033,024 Zimmermann Sept. 12, 1911 2,843,168 Lunn July 15, 1958 2,904,085 Wennberg Sept. 15, 1959 2,918,952 Searle Dec. 29, 1959 2,985,206 Letts May 23, 1961 FOREIGN PATENTS 537,677 Canada Mar. 5, 1957 Finland Aug. 15, 1955 

